Fig. 684Fig. 684.
Fig. 684.
This, however, is a theoretical, rather than a practical point, as may be perceived fromFig. 684, in whichris a part of a section of a roll, andwa part of a section of a wheel. Now, assuming that theV-ways were as much as even a sixteenth out of true, so far as height is concerned, all the influence of the variation in height is shown by the second line of emery-wheel perimeter, shown in the figure, the two arcs being drawn from centres, one of which is1⁄16th inch higher than the other. It is plain, then, that with the ordinary errors found in suchV-guideways, which will not be found to exceed1⁄30th of an inch, no practical effect will be produced upon the roll. Again, if oneVis not in line with the other, no practical effect is produced, because if the carriagecwere inclined at an angle, though the plane of rotation of the emery-wheel would be varied, its face would yet be parallel to the roll axis. If theVs were to vary in their widths apart (the angles of theVs being 45° apart), all the effect it would have would be to raise or lower the carriagecto one-half the amount theVs were in error. It will be thus perceived that correctness of the roll both for parallelism and cylindricity is obtained independent of absolute truth in theV-guides.
Fig. 685Fig. 685.
Fig. 685.
Referring now to some of the details of construction of the lathe, the slide resta,Fig. 683, is bored to receive socketsd d,Fig. 685, and is provided with caps, so that the sockets may be firmlygripped and held axially true one with the other. The socket-bores are taper, to receive the taper ends of the arborx, and are provided with oil pockets at each end. There is a driving pulley on each side of the emery-wheel, and equal belt-speed is obtained as follows: Two belt driving drumsm nare employed, and each belt passes over both, as inFigs. 683and685, and down around the pulleysp. The diameter of the drumnis less than the diameter of the drummby twice the thickness of the belt, thus equalizing inside and outside belt diameters, since they both pass over the pulley of the emery-arbor. The piecetis a guard to catch the water from the emery-wheels, and is hinged at the back so that the top is a lid that may be swung back out of the way when necessary.
Fig. 686Fig. 686.
Fig. 686.
Fig. 687Fig. 687.
Fig. 687.
The method of securing the emery-wheels is shown inFig. 686. Two flangesz(made in halves) are let into the wheel, and clamp the wheel by means of the screws shown. The bore of these flangeszis larger than the diameter of pulleysp, so that the emery-wheels may be changed on the arbor without removing the pulley.Fig. 687represents an end view of the bearingsbfor the roll to revolve in, being provided with three pieces, the two side ones of which are adjustable by the set-screws, so as to facilitate setting the roll parallel with the bed of the lathe. The height is adjusted by means of screwsk,k, which may also be used in grinding a roll of large diameter at the middle of its length, by occasionally raising the roll as the carriagecproceeds along the roll (the principle of this action ishereafterexplained with reference to turning tapers on ordinary lathe work). When the wheels have traversed half the length of the roll, the screwskare operated to lower it again, it being found that the effect of a slight operating of the screwskis so small that the workman’s judgment may be relied upon to use them to give to a roll with practical accuracy any required degree of enlarged diameter at the middle of its length with sufficient accuracy for all practical purposes.
There are, however, other advantages of this system, which may be noted as follows. When a single emery-wheel is used there is evidently twice the amount of wear to take a given amount of metal off (per traverse) that there is when two wheels are used, and furthermore the reduction of every wheel diameter per traverse is evidently twice as great with one wheel as it is with two. From some experiments made by Messrs. Morton Poole, it was found that using a pair of 10-inch emery-wheels it would take 40,000 wheel traverses along an average sized calender roll, to reduce its diameter an inch, hence the amount of error due to the reduction of the emery-wheel diameters, per traverse, may be stated as1⁄40000of an inch per traverse, for the two wheels.
Fig. 688Fig. 688.
Fig. 688.
Now referring toFig. 688, letrrepresent a roll andw wthe two emery-wheels.
Suppose the wheels being at the end of a traverse, the roll is1⁄40000inch larger at that end on account of the wear of the emery-wheels, then each wheel will have worn1⁄40000inch diameter or1⁄80000inch radius, hence the increase of roll diameter is equal to the wear of wheel diameter.
Fig. 689Fig. 689.
Fig. 689.
Now, suppose that one wheel be used as inFig. 689, and its reduction ofdiameterwill be equal to that of the two wheelsadded together, or1⁄20000inch, this would be1⁄40000in the radius of the wheel, producing a difference of1⁄20000difference in the diameter of the wheel.
There is another advantage, however, in that a finer cut can be easier put on in thePoole system, because if a feed be put on of1⁄100th inch, the roll is only reduced1⁄100th inch in diameter, but if the same amount of feed be put on with a single wheel, it will reduce the roll1⁄50th inch, hence for a given amount of feed or movement of emery-wheel towards the roll axis, the amount of cut taken is only half as much as it would be if a single wheel is used. This enables a minimum of feed to be put on the wheel, wear being obviously reduced in proportion as the feed is lighter and the duty therefore diminished.
The method of driving the roll is as follows: Shaftt,Fig. 681, runs in bearings in the head, and spindler r′passes through, and is driven by shaftt. A driving pulley is fitted on the spindle at endr′, at the other end is a driving chuckpfor driving the roll through the medium of awabbler, whose construction will be shown presently. Spindlermay be adjusted endwise int, so that it may be adjusted to suit different lengths of rolls without moving the bearing blocksb.
Fig. 690Fig. 690.
Fig. 690.
The wabbler is driven bypand receives the end of the roll to be ground, as shown inFig. 690, the end of the roll being a taper square and fitting very loosely in a square taper hole in the end of the wabbler; similarlypmay have a taper square hole loosely fitting the squared end of the wabbler. The looseness of fit enables the wabbler to drive the roll without putting any strain on it tending to lift or twist it in its bearings in blockb, and obviates the necessity for the axis of the rolls to be dead in line with the axis ofr r′. Various lengths of wabblers may be used to suit the lengths of roll and avoid moving blocksb, and it is obvious also that if the ends of the roll are round instead of square, two set-screws may be used to hold the roll end being set diametrically opposite, and if set screws are used inpto drive the wabbler they should be two in number, set diametrically opposite, and at a right angle to the two in the wabbler, so that it may act as a universal joint.
The method of automatically traversing the carriagecis as follows: Referring toFig. 681, two gearsa,bare fast upon shaftt, gearadrivescwhich is on the same shaft ase, gearbdrivesdwhich drives a gear not seen in the cut, but which we will termx, it being on the same shaft ascande. Now ifeis driven through the medium ofa c, it runs in one direction, while if it is driven through the medium ofb d x, it revolvesein the opposite direction, and sinceedrivesgandgis on the end of the feed screw (e,Fig. 682) the direction of motion of carriagecis determined by which of the wheelsaorbdrivese. Athis a stand affording journal bearing to a shaftn, whose end engages a clutch upon the shaft of wheelsc,xande. On the outer end of shaftnis ball leverl′′, whose lower end is attached to a rodk, upon which are stopsl l′adjustable along rodkby means of set-screws. Atmis a bracket embracing rodk.
Now suppose carriagecto traverse to the left, andmwill meetlmoving rodkto the left, the balliwill move up to a vertical position and then fall over to the right, causing the clutch to disengage from gearcand engage with the unseen gearx, reversing the motion ofeand ofg, and therefore of carriagec, which moves to the right untilmmeetsl′and pushes it to the right, causingito move back to the position it occupies in the engraving, the clutch engagingc, which is then the driving wheel fore.
Screw Machine.—The screw machine is a special form of lathe in which the work is cut direct from the bar, without the intervention of forging operations, and it follows therefore that the bar must be large enough in diameter to suit the largest diameter of the work, the steps or sections of smaller diameter being turned down from the full size of the bar. The advantages of the screw machine are, that the work requires no centring since it is held in a chuck, that forging operations are dispensed with, that any number of pieces may be made of uniform dimensions without any measuring operations save those necessary when adjusting the tool for the first piece, and that it does not require skilled labor to operate the machine after the tools are once set.
The capacity of the screw machine is, therefore, many times greater than that of a lathe, while the diameters and lengths of the various parts of the work will be more uniform than can be done by caliper measurements, being in this case varied by the wear of the cutting edges of the tools only, which eliminates the errors liable to independent caliper measurement. Hollow work, as nuts and washers, may be equally operated on being driven by a mandril held in the chuck.
Fig. 691represents Brown and Sharpe’s Number 1 screw machine, which is designed for the rapid production of small work.
Three separate tool-holding devices may be employed: first, cutting tools may be placed in the holes shown to pierce (horizontally) the circular headf; second, tools may be fixed in the tool posts shown in the double slide rest, which has two slides (one in the front and one at the back of the line of centres); and third, tools may be placed in what may be termed the screw-cutting slide-restj.
fis a head pierced horizontally with seven holes, and is capable of rotation uponl; when certain mechanism is operatedlslides ondand the mechanism of these three parts is arranged to operate as follows. The lever armsktraverselind. Whenkis operated from right to left,ladvances towards the live spindle until arrested at some particular point by a suitable stop motion, this stop motion being capable of adjustment so as to allowfto approach the live spindle a distance suitable for the work in hand.
When, however,kis operated from left to rightlmoves back, and when it has traversed a certain distance, the headfrotates1⁄7of a rotation, and becomes again locked so far as rotation is concerned. Now the relation between the seven holes infis such that whenfhas rotated its1⁄7rotation, one of the seven holes is in line with the live spindle. Suppose then seven cutting tools to be secured in the holes inf, thenkmay be operated from right to left, traversinglandfforward, and one of the cutting tools will operate upon the work untillmeets the stop;kmay then be moved from left to right,landfwill traverse back, thenfwill rotate1⁄7rotation andlandfmay be traversed byk, and a second tool will operate upon the work, and so on.
The diameter of the work is determined by the distance of the cutting edge of the tool from the line of centres, when such tool is in line with the work, or, in other words, is in position to operate upon the work. The end measurements of the work are secured by placing the cutting edges of the tools the requisite distance out fromf, whenlis moved forward as far as the stop motion will permit. But it is evident that the length of cut taken along the work, would under these simple conditions vary with the distance of the end of the work from the face of the chuck driving it, but this is obviated asfollows:—
The live spindle is made hollow so that the rod of metal, of which the work is to be made, may pass through that spindle. A chuck on the spindle holds the work or releases it in the usual manner. Suppose then the chuck to be open and the bar free to be moved, then there is placed in the hole inf, that is in line with the work, a stop instead of a cutting tool. The end of the work may then, for the first piece turned, be squared up by a tool placed in the slide rest and then released from the chuck and pushed through the live spindle until it abuts against the stop so adjusted and affixed in the hole inf;kmay then be operated to act on the work. The first tool may reduce the work to its largest required diameter, the second turn down a plain shoulder, the third may be a die cutting a thread a certain distance up the work, the fourth may be a tool turning a plain part at the beginning of the thread, the fifth may round off the end of the work, and the sixth may be a drill to pierce a hole a certain distance up the end of the work.
Now suppose the work to require its edge at the other end to be chamfered, then there may be placed in the slide rest tool posts a tool to sever the work from the bar out of which it has beenmade, while the other may be used to chamfer the required edge, or to round it if needs be to any required form.
Work held in the chuck but not formed from a rod may be, of course, operated upon in a similar manner.
In the case, however, of work of large diameter requiring to be threaded, the threading tool may be held and operated differently and more rigidly as follows.iis a lever carrying under its bend and over the projecting end of the live spindle, a segment of a nut whose thread must equal in pitch the pitch of thread to be given to the work. A collar or ring, oftentimes called the leader, having a thread of the same pitch, is then secured upon the live spindle, so as to rotate with it, and have no end motion; when thereforeiis depressed, the nut will come into work with the collar or ring, andiwill be traversed at a speed proportioned to the pitch of the threads on the collar and nut.
Nowiis attached to a shaft having journal bearing (and capable of end motion) at the back of the lathe head, and on this bar is attached the slide restj, in which the turning or threading tool may be placed. The shaft above referred to having end motion, may be operated (when the nut in the leveriis lifted clear of the collar) laterally by means of the leveri; hence to traversejto the right, or for the back traverse,iis raised and pulled to the right,iis then lowered, the nut engages with the collar, and the tool is traversed to the cut. The cut is adjusted for diameter by the slide rest, which is provided with an adjustable stop to determine the depth to which the tool shall enter the work.
It is obvious that this part of the machine, may be employed for ordinary turning operations, if the collar be of suitable pitch for the feed.
Fig. 693Fig. 693.
Fig. 693.
Figs. 692and693represent a screw machine for general work.
ais a chuck with hardened steelV-shaped jaws. It is fast on the hollow arbor of the machine.bis a steadying chuck on the rear end of the arbor. The arbor has a two and one-sixteenth hole through it and its journals are very large and stiff. It is of steel, and runs in gun-metal boxes. The cone pulley and back gear is of the full proportion and power of an eighteen-inch lathe.cis an ordinary lathe carriage fitted to slide on the bed, and be operated by hand-wheeldand a rack pinion as usual. Across this carriage slides a tool resteoperated by screw as usual, and having two tool posts, one to the front and one to the rear of the work. This tool rest, instead of sliding directly in the carriage as is the case with lathes, slides on an intermediate slide which fits and slides in the carriage. This intermediate slide is moved in and out, a short distance only, by means of cam leverg. An apron on the front end of this slide carries the lead screw nuth. When the cam lever is raised it brings the slide outward about half an inch, and the tool restecomes out with it and at the same time the nut leaves the lead screw. The inward movement of the slide is always to the same point, thus engaging the lead screw and resetting the tool. In cutting threads with a tool in the front tool post the tool is set by moving the tool rest as usual, and at the end of the cut the cam lever serves to quickly withdraw the tool and lead screw nut so that the carriage can be run back. The tool rest is then advanced slightly and the new cut taken. By this means threads are cut without any false motions, and the threads may be cut close up to a shoulder.
iis the lead screw. This screw does not extend, as is usual, to the head of the machine. It is short and is socketed into a shaft which runs to the head of the machine and is driven by gearing as usual. The lead screw is thus a plain shaft with a short, removable, threaded end. The gearing is never changed. Different lead screws are used for different threads, thus permitting threads to be cut without running back. The lead screws are changed in an instant by removing knobj. The lead screw nuthis a sectional nut, double ended, so that each nut will do for two pitches, by turning end for end in the apron.lis an adjustable stop which determines the position of the carriage in cutting off, facing, &c.kis an arm pivoted to the rear of the carriage and carrying three open dies like a bolt cutter head. Atmis a block sliding or capable of being fed along the bed.nis a gauge screw attached to this block and provided with two nuts. The stop lever shown in the cut turns up to straddlethis screw, and the position of the nuts determines how far each way the block may slide.ois the turret fitted to turn on the block. It has six holes in its rim to receive sundry tools. It can be turned to bring any of these tools into action, and is secured by the lock leverp.
The turret slide is moved quickly by hand, by means of the capstan leversu, which, by an in-and-out motion, also serve to lock the turret at any point. The turret slide is fed, in heavy work, by the crank-wheelron its tail screw. This tail screw carries, inside the crank-wheel, two gearss, which are driven at different speeds by a back shaft behind the machine. These two gears are loose on the tail screw, and a clutch operated by levertlocks either one to the screw. Both the carriage and turret are provided with oil pots not shown in the cuts.
Fig. 694Fig. 694.
Fig. 694.
A top view of the turret is shown inFig. 694, a set of tools being shown in place.
Fig. 695Fig. 695.
Fig. 695.
Fig. 696Fig. 696.
Fig. 696.
The end gauge which is shown removed from the chuck inFig. 695, is composed of a hollow shankafitting the hole in the turret, and a gauge rodbfitting the bore of the shank. The shankamay be set farther in or out of the turret, and the rodbmay be set farther in or out of the shank, the two combined being so set that when the turret is clear back against its stop the end of the rodbwill gauge the proper distance that the bar iron requires to project outwards from the chuck of the machine. The centre shown inFig. 696corresponds to an ordinary lathe centre, and is only used when chasing long work in steel.
Fig. 697Fig. 697.
Fig. 697.
The turner shown removed from the chuck inFig. 697, consists of a hollow shanka, fitting the turret and having at its front end a hardened bushingbsecured toaby a set screw. It has also a heavy mortised boltcin the front lug of the shank; an end-cutting tooldshaped like a carpenter’s mortising chisel, and clamped by the mortised bolt; a collar screweto hold the tool endwise; and a pair of set-screwsfto swivel the tool and its bolt. Bushingbis to suit the work in hand. The tooldis a piece of square steel hardened throughout. It is held by its bolt with just the proper clearance on its face. It cuts with its end without any springing, and will on this account stand a very keen angle of cutting edge. There is hardly any limit to its cutting power. It will cut an inch bar away at one trip with a coarse feed. It does not do smooth work, and is, therefore, used only to remove the bulk of the metal, leaving the sizer to follow.
Fig. 698Fig. 698.
Fig. 698.
The sizerFig. 698, consists of a hollow shankafitting the turret and carrying in its front end a hardened bushingband a flat cutting toolc. The sizer follows the turner and takes a light finishing cut with oil or water, giving size and finish with a coarse feed, and having only a light and clean duty it maintains its size.
Fig. 699Fig. 699.
Fig. 699.
Fig. 700Fig. 700.
Fig. 700.
The die holder shown inFigs. 699and700, is arranged to automatically stop cutting when the thread is cut far enough along the work. It will cut a full thread cleanly up against a solid shoulder. It consists of a hollow shankafitting the turret; a sleevebfitted to revolve and slide on the front end of the shankc; a grooveebored inside the sleeve; a pindon the shank fitting freely in the groovee; a keywayfat one point in the groove and leading out each way from it; and a thread diegheld in the front end of thesleeve. When the turret is run forward, the thread die takes hold of the bolt to be cut, but it revolves idly instead of standing still to cut, until the pindcomes opposite the keywayfwhen, the turret still being moved forward, the pin enters the back of the keyway. The sleeve now stands still, the die cuts the thread and pulls the turret along by the friction of the pin in the keyway. Finally the turret comes against its front stop and can move forward no farther. Consequently the sleeve is drawn forward on its shankc, and the instant the pindreaches the grooveethe die and sleeve commence to revolve with the work and cease cutting. The machine is then run backward, and the turret moved back a trifle. This causes the pin to catch in the front end of the keyway and the sleeve is again locked. The die then unscrews, and, in doing so, pushes the turret back. A tap holder may be inserted in place of the die, and plug taps may be run to an exact depth without danger.
Drills and other boring tools are held in suitable sockets, which fit into the turret.
The following are the operations necessary to produce in this machine an hexagon-headed bolt.
Fig. 701Fig. 701.
Fig. 701.
First operation: The bar is inserted through the open chuck.
Second operation: Turret being clear back against its stop and revolved to bring present the end gauge, the bar is set against the end gauge, and the chuck is tightened. This chucks the bar and leaves the proper length projecting from the chuck.
Third operation: Front tool in the carriage, a bevelled side tool cones the end of the bar so turret tools will start nicely.
Fourth operation: Turret being revolved to present the turner, the bar is reduced, at one heavy cut, to near the proper size, the turret stop determining the length of the reduced portion.
Fifth operation: Turret being revolved to present the sizer, the body of the bolt is brought to exact size by a light, quick, sliding cut.
Fig. 702Fig. 702.
Fig. 702.
Sixth operation: Open die arm being brought down, the bolt is threaded; the left carriage stop indicating the length of the threaded part.
Seventh operation: Turret being revolved to present the die holder, the solid die is run over the bolt, bringing it to exact size with a light cut, and cuttingfull thread to the exact point desired.
Eighth operation: Front tool in the carriage chamfers off the end thread.
Ninth operation: Back tool of carriage, a parting tool, cuts off the bolt; the left carriage stop determining the proper length of head.
Tenth operation: Bolt being reversed in chuck, the top of the head is water cut finished by a front tool in the carriage. This operation is deferred till all the bolts of the lot are ready for it.
Fig. 703Fig. 703.
Fig. 703.
Fig. 703represents a general view of a screw machine designed by Jerome B. Secor, of Bridgeport, Connecticut. The details of the machine are shown inFigs. 704,705,706,707,708,709,710, and711.[13]The live spindle is of steel and is hollow, and its journals are ground. The boxes are lined with babbitt, so that no other metal touches the spindle, and may, by a special device, be re-babbitted and bored exactly parallel with the planing of the bed.
[13]FromMechanics.
[13]FromMechanics.
Fig. 704Fig. 704.
Fig. 704.
A steel collarj,Fig. 704, between the front end of the forward box and the spindles, receives the thrust due to the cut, and a nut on the spindle acts against the cone to adjust it forward on a featherkin the spindle to take up end wear. The wire or rodfrom which the work is to be made is passed through the spindle and collar on the stand, and is held by a thumb-screw in the collar, which is influenced by the weight and cords, so that when the wire is released in the chuck the weight pulls the collar and wire forward, forcing the wire out through the front end of the chuck until it comes against the stop in the turret, which gauges the length needed to make the piece required. From time to time, as the rod is used up, the thumb-screw in the sliding collar is loosened, and the collar is shoved back on the rod as far as it will go, and the set-screw is again tightened.
Fig. 704shows in section the front bearing and the automatic chuck.mis a hollow spindle within which is the hollow spindleh, through which the rod or wire to make the work passes. It is prevented from end motion by the cone hub on one side and the collarjon the other side of the bearing, whilehmay be operated endwise withinmby means of the hand-lever shown on the left-hand of the headstock in the general view. The coreaof the chuck screws uponm, and is threaded to receive the adjustment nutb, which receives and holds the adjustment wedgescat their ends by the talon shown. The shelldis secured tohby the screwsi, which pass through slots ina, and therefore move endwise whenhis operated by its hand-lever. Now the mouth ofd, against which the adjustment wedgescrest, is coned 21⁄2°, as marked; hence the end motion ofdto the left causesc, and thereforef, to approach the axis of the chuck and grip the rod or wire, while its motion to the right causesc, and thereforef, to recede from the chuck axis and to release the wire. Sincebis screwed upona, andcis guided at the end byb, and since alsofis detained endwise ina, the motions ofcand offare at a right angle to the chuck axis. Hence in gripping the rod or wire there is no tendency to move it endways, as there is where the gripping jaws have, as in many machines, a certain amount of end motion while closing. When this end motion exists, tightening the jaws upon the work draws it away from the stop in the turret and impairs the adjustment for length of work. The gripping jaws are closely guided in slots indand ina, and three sets of these jaws are necessary to cover a range of work from the full diameter of the bore ofhdown to zero. The capacity of each of these sets of jaws, however, may be varied as follows: The adjustment ringbis threaded upona, and may be operated alongato movecendwise by means of the tangent screwe, whose threads engage with teeth parallel to the axis ofb, and running across its width all around its circumference, hence rotatinge, rotatesb, causing it to move alonga, and carrycbeneathf. By this method of adjustmentfneed be given only enough motion to and from the chuck axis to grip and release the work, and the reduction of motion between the hand-lever operatinghand the motion offis so great, that with a very moderate force at the lever the wire may be held so that its projecting end may be twisted off without slipping the wire within the jaws or impairing the jaw grip.
Fig. 705Fig. 705.
Fig. 705.
Fig. 706Fig. 706.
Fig. 706.
Fig. 705is a sectional and end view of the coreaof the chuck, andFig. 706a sectional and end view of the shelld.
Largeimage(83 kB).Fig. 707Fig. 707.
Largeimage(83 kB).
Fig. 707.
Fig. 707represents a sectional side view and an end view of the cross slide, or cutting-off slide, which carries two tool posts, and therefore two cutting tools, one of which is at the back of the rest. In place of a feed screw and nut, or of a hand lever and link, it is provided with a segment of a gear-wheelpoperating in a rackr, which avoids the tendency to twist the cross slides in its guides which exists when a hand lever and link is used.
The cross slide is adjusted to fit in its guideway by a jaws1,Fig. 707, which is firmly screwed to and recessed intor. To take up the wear, the face ofs1is simply reduced. This possesses a valuable advantage, because it is rigid and solid, does not admit of improper adjustment, nor can the adjustment become impaired at the hands of the operator.
To adjust the position of the cross slide upon the shears a screw passes between the shears and is threaded into the studq. This screw is operated by a hand wheel shown in the general view,Fig. 703, beneath the rear bearing of the headstock.
A special and excellent feature of the machine is the stop device for the motion of the cross slide which is shown inFig. 707.
The screwshas one collarc, solid on it, and the screwed end is tapped into the sliding sleevet, which is held from turning by the studa. Between the solid collarcand the loose collarbthere is a short, stiff spiral spring, as shown; by means of the fast and loose collars, the spring and the screwed thimbled, a strong friction is had on the collarb, which is ample to keep the screw from turning while in use as a stop, although it permits the screw to turn easily enough when a wrench is applied to the square end. Precisely the same device is used at the other end of the slide to stop it in the opposite direction.
Fig. 708Fig. 708.
Fig. 708.
Fig. 709Fig. 710Fig. 709.Fig. 710.
Fig. 709.Fig. 710.
Details of the mechanism of the turret and turret slide are shown inFigs. 708,709, and710.Fig. 708is an end sectional view of the turret slide, which is traversed on its base by a segmentdof a gear operating in a rackr(in the same manner as the cutting-off slide), the segment being connected by studnto handlem.orepresents the body of the slide, which is grooved at the sides to receive the gibsx, which secure it to the basepon which it slides.pis clamped to its adjusted position on the shears or bed by means of the gib, shown in dotted lines, which is pulled laterally forward by the screws, which is tapped into the stem of the gib. The method of rotating the slide and of locking it in position is shown inFig. 709, which is a top view of the turret head, andFig. 710, which showsoremoved frompand turnedupside down. Pivoted to segmentdis a rodehaving atka pin that as motion proceeds falls intosand rotatest, which is fast to the bottom of the turret. Upon the handlembeing moved backward the segment begins its motion forward, as indicated by the arrow inFig. 710, thereby moving the slide backward upon the gibs by the working of its cogs into the rackr,Fig. 708, which is attached to the basep. When the segmentdhas accomplished about one-half its motion the pinh, which is on the upper side of the segmentd, comes in contact with the projection or lug on the side of the camf, as shown by the arrow head inFig. 710, bringing the opposite side of the cam against the ping,Fig. 709, thereby moving it backward, compressing the springu, and drawing the boltlfrom its seat in the discv. This operation is completed before the motion of the segment brings the pinkin contact with the ratchet-wheelt. The segmentdin continuing its motion after the pinkis brought into the notchs, begins the revolution of the turret on its axis. As will be seen by the inspection ofFig. 710, the pinhworks upon a much longer radius than the projection upon the cam with which it comes in contact, and therefore, after a given part of its motion is complete, gets beyond the reach of the cam, thereby releasing its hold and allowing the boltl,Fig. 709, to be forced against the discvby the expansion of the springu, which occurs soon after the turret has commenced its revolution by the contact of pinkwith the wheelt. The completion of the movement of the handlem(and the segmentd) completes the revolution of the turret one-sixth of its circumference, thereby allowing the boltl, by the further expansion of the springu, to be forced into its next opening or seat in the discv. The forward motion of the handlembrings the turret forward to its position at the work and restores the parts to their former positions, as shown in the illustrations.